Everyone knows that ‘correlation is not causation’ – that just because two things tend to happen together, it doesn’t mean that one of them causes the other.
However, what few people realize – except scientists – is that there’s a handy exception to this rule. This is when the two things are ‘linked’.
You see, if two things are correlated, then they can be described as ‘linked’. But if one thing causes the other, that also makes them ‘linked’.
So correlation = linked = causation, or in other words: correlation = causation! The logic’s unassailable, I’m sure you’ll agree.
‘Linked’ is a very popular word in neuroscience and biology. A great many things have been linked to each other and the word often serves, I fear, to make science less scientific.
If the evidence doesn’t support a certain causal association, but you want to imply that it does, you can use ‘linked’. If all the signs do point to causation, and you want to downgrade it to a correlation, you can use the L-word. It’s very versatile.
Correlation and causation are quite distinct. In describing them we ought to be clear. A wide gulf seperates them, but ‘linked’ bridges the gap: it’s a vague term that, in failing to specify the nature of an association, allows it to be read as anything.
‘Linked’ is not alone however. A linked phrase is ‘involved in’, as in “Brain region X is involved in memory”.
This is not quite as bad, as it does imply some kind of causation, but it’s often used in such a nonspecific way that it’s all but meaningless.
- Hitler and Churchill were both involved in WW2.
- Democrats and Republicans were both involved in the election of Barack Obama.
- Neuroskeptic and his laptop are both involved in writing this post.
All true, and all pretty pointless.
Linked and similar terms are a verbal fudge, or just linguistic gum to connect two ideas in the hopes that the reader will mentally confuse them. This kind of loose attitude to relating concepts is the stuff of poetry and rhetoric. It does science no good.